Alert archive / Arizona / Flash Flood Warnings in 2021

Flash Flood Warning 171, NWS Tucson, AZ

September 29, 2021Pima County, Arizona

NWS Tucson, AZ issued this flash flood warning at Sep 29, 2021, 11:08 PM MST for Pima County, Arizona. It was in force for 112 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Sep 29, 2021, 11:08 PM MST (06:08 UTC)
Expired: Sep 30, 2021, 1:00 AM MST
In force: 112 min
Issued by: NWS Tucson, AZ
Area: Storm-based polygon
Damage threat: Considerable
Flood severity: None

County Pima County, AZ

The radar

The Phoenix radar (KIWA), 127 km from the middle of the area, began a volume at 06:11 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

The nearest sounding before it

Tuscon, AZ (KTUS), launched 00:00Z, 6.1 hours before the alert went out and 121 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 314 J/kg
Mixed-layer CIN: -91 J/kg
Mixed-layer LCL: 2898 m above ground
0-6 km bulk shear: 31 kt
0-1 km storm-relative helicity: 11 m²/s²
0-3 km storm-relative helicity: 31 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.4

Open this sounding in Storm Lab

The text

As transmitted.

639 
WGUS55 KTWC 300608
FFWTWC
AZC019-300800-
/O.NEW.KTWC.FF.W.0171.210930T0608Z-210930T0800Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Tucson AZ
1108 PM MST Wed Sep 29 2021

The National Weather Service in Tucson has issued a

* Flash Flood Warning for...
  North Central Pima County in southeastern Arizona...

* Until 100 AM MST.

* At 1108 PM MST, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 1 and 2 inches of rain 
  have fallen. Flash flooding is ongoing or expected to begin 
  shortly.

  HAZARD...Life threatening flash flooding. Thunderstorms
           producing flash flooding.

  SOURCE...Radar.

  IMPACT...Life threatening flash flooding of creeks and streams,
           urban areas, highways, streets and underpasses.

* Some locations that will experience flash flooding include...
  Covered Wells and Mountain Village.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around, don't drown when encountering flooded roads. Most flood 
deaths occur in vehicles.

Be especially cautious at night when it is harder to recognize the 
dangers of flooding.

Remain alert for flooding even in locations not receiving rain. 
Washes, streams, and rivers can become raging killer currents in a 
matter of minutes, even from distant rainfall.

&&

LAT...LON 3231 11222 3223 11203 3211 11212 3221 11231

FLASH FLOOD...RADAR INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE

$$

RH

1 follow-up statement

654 
WGUS75 KTWC 300752
FFSTWC

Flash Flood Statement
National Weather Service Tucson AZ
1252 AM MST Thu Sep 30 2021

AZC019-300802-
/O.EXP.KTWC.FF.W.0171.000000T0000Z-210930T0800Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Pima AZ-
1252 AM MST Thu Sep 30 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 1 AM MST EARLY THIS MORNING 
FOR NORTH CENTRAL PIMA COUNTY...

The heavy rain has ended. Flooding is no longer expected to pose a 
threat. Please continue to heed remaining road closures.

LAT...LON 3231 11222 3223 11203 3211 11212 3221 11231

$$

JD

The office that day

Everything else NWS Tucson, AZ issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Sep 29, 11:25 PM MST	Areal Flood Advisory	TWC	Pima	3 hr
Sep 29, 11:51 PM MST	Flash Flood Warning	TWC	Pima	3 hr
Sep 29, 11:57 PM MST	Severe Thunderstorm Warning	TWC	Pinal	48 min
Sep 30, 12:13 AM MST	Severe Thunderstorm Warning	TWC	Pima	47 min
Sep 30, 12:24 AM MST	Areal Flood Advisory	TWC	Pima, Pinal	3 hr
Sep 30, 12:40 AM MST	Severe Thunderstorm Warning	TWC	Pinal	50 min
Sep 30, 12:57 AM MST	Special Weather Statement	TWC	Pinal	33 min
Sep 30, 3:21 AM MST	Special Weather Statement	TWC		39 min
Sep 30, 4:05 AM MST	Areal Flood Advisory	TWC	Cochise	115 min
Sep 30, 12:58 PM MST	Special Weather Statement	TWC	Santa Cruz	47 min
Sep 30, 2:23 PM MST	Areal Flood Advisory	TWC	Cochise	97 min

Nearby

Flash Flood Warnings in Arizona, 2021 Every flash flood warning in 2021

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.